Apparatus for continuously producing tubular foamed polyurethane insulation

ABSTRACT

Apparatus for continuously producing tubular foamed polyurethane insulation in which a liquid foamable polyurethane composition is supplied to a rotary ring dispenser which centrifugally sprays the liquid onto a flexible sleeve positioned around and spaced from a pipe. The sleeve and dispensed liquid are moved axially relative to the dispenser and the outer surface of the sleeve is supported while the liquid foams and expands radially to fill the space between the pipe and the sleeve.

United States Patent Van Dijk Mar. 19, 1974 [5 APPARATUS FORCONTINUOUSLY 3.354.244 11/1967 Davidson 425/4 c x PRODUCING TUBULAR F E3.443.276 5/1969 Smith et al...

3,649,730 3/1972 Benteler et al 425/4 C X POLYURETHANE INSULATIONInventor: Jan C. Van Dijk, Delft, Netherlands Assignee: Shell OilCompany, New York, N.Y.

Filed: Oct. 25, 1972 Appl. No.: 300,695

Related US. Application Data Division of Ser. No. 8l5,l29, April 10,1969, Pat. No. 3,733,382.

US. Cl 425/110, 264/47, 264/309, 425/122, 425/392, 425/817 C Int. Cl829d 27/00 Field of Search 425/103. 110, 817, 817 C, 425/4, 4 C, 329.111, 114, 122, 392, 393; 264/47, 51, 262, 309

Primary Examiner-R. Spencer Annear Assistant Examiner-Mark RosenbaumAttorney, Agent, or Firm-Fredrik Marlowe [57] ABSTRACT Apparatus forcontinuously producing tubular foamed polyurethane insulation in which aliquid foamable polyurethane composition is supplied to a rotary ringdispenser which centrifugally sprays the liquid onto a flexible sleevepositioned around and spaced from a pipe. The sleeve and dispensedliquid are moved axially relative to the dispenser and the outer surfaceof the sleeve is supported while the liquid foams and expands radiallyto fill the space between the pipe and the sleeve.

3 Claims, 4 Drawing Figures PATENTEB MAR 19 I974 SHEET 2 UP 3 FIG. 2

APPARATUS FOR CONTINUOUSLY PRODUCING TUBULAR FOAMED POLYURETHANEINSULATION This is a division, of application Ser. No. 815,129, Pat. No.3,733,382filed Apr. 10, 1969.

BACKGROUND OF THE INVENTION The invention relates to a method andapparatus for continuously producing tubular foamed polyurethaneinsulation.

Foamed polyurethane is a natural wall known for its outstandingqualities as a thermal insulant. It can be made in the form of rigidinsulation scales ready for application on a pipe or other surface to beinsulated. Alternatively, the insulation can be made in situ by pouringor spraying a liquid, foamable polyurethane composition directly on thesurface of a pipe, tank wall or other body to be insulated.

Although foamed polyurethane is an excellent insulating material, itsuse is on the whole rather more expensive than some of the moreconventional insulation materials such as glass wool or asbestos wool.One reason is the slow and therefore costly production of the ready-madescales in individual moulds in a discontinuous process. According to analternative method in which a foamable polyurethane coating is appliedby spraying directly on a pipe continuous production is possible, but inthis way a regularly shaped insulation around and along the pipe cannotbe obtained. Moreover, high material losses occur, and outdoorapplication on existing pipelines is highly weather and wind de'pendent. Still other methods have the same or different shortcomings,for example, they do not produce an insulation of constant density andcell size, are difficult to practice or cannot be used at all forpipelines already laid in the field.

SUMMARY OF THE INVENTION Therefore it is the object of the invention toprovide a method which allows fast, simple and continuous production ofa foamed polyurethane insulation having satisfactory qualities.

According to the invention a method of continuously producing tubularfoamed polyurethane insulation comprises feeding a liquid, foamablepolyurethane forming composition or its components to a rotary ringdispenser mounted rotatably around a pipe which is positioned coaxiallywithin a flexible, tubular body or sleeve; rotating the dispenser aroundthe pipe whereby the received liquid composition is dischargedcentrifugally from the dispenser as a spray onto the inner face of theflexible tubular body, the dispenser simultaneously and continuouslybeing moved axially relative to the tubular body; allowing the liquidcomposition on the tubular body to foam and thereby expand radially tofill the space between the pipe and tubular body whilst supporting thetubular body at its outer face, and allowing the foamed polyurethane toharden. The invention further provides an apparatus for continuouslyproducing tubular foamed polyurethane insulation according to the abovemethod, comprising a rotary ring dispenser having a central openingtherein, centering means for mounting a pipe coaxially with thedispenser through the central opening thereof, driving means forrotating the dispenser on its axis, supply means for feeding a liquid,foamed polyurethane forming composition to the dispenser, the reelholding means adapted to hold a plurality of reels of sheet material ina regular arrangement with respect to the circumference of thedispenser, and a tubular support mounted coaxially with and extendingaround the dispenser for supporting the sheet material when drawn offthe reels and through the support.

The centrally located pipe can be an internal calibration pipe forsizing the internal diameter of the tubular insulation. The calibrationpipe is moved simultaneously with the dispenser in the axial direction,whereby the calibration pipe is continuously being withdrawn from thepolyurethane tube produced around the pipe. To avoid adherence of thepolyurethane to the calibration pipe the surface of this pipe is made ofa release material such as polypropylene or another polyolefinicmaterial, or polytetrafluoroethylene. The formed polyurethane tube canbe cut in sections of the desired length, and these sections in turn canbe cut lengthwise to form two identical halves suitable for mountingaround a pipeline to be insulated.

Alternatively, the pipe through the central opening of the dispenser isa pipe to be insulated in situ. In that case the insulation is to remainon the pipe, and therefore the pipe will move jointly with the movingsheets forming the tubular body of paper or other flexible materialaround it. The pipe may form part of a pipeline already laid in thefield, in which case the invention is particularly meritorious since theassembly of dispenser, means of supplying the polyurethane composition,means for rotating the dispenser, reels with paper sheets, and guidemeans for the paper sheet can be mounted on a common frame designed as avehicle adapted to travel over the pipeline to be insulated.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be furtherexplained by way of example with reference to the accompanying.diagramatic drawing, in which:

FIG. 1 is an elevational view partly in section of one embodiment of theapparatus of the invention used for insulating pipe;

FIG. 2 is an elevational view of an apparatus similar to the one of FIG.1 but adapted for making prefabricated pipe scales;

FIG. 3 is a perspective view of an apparatus similar to the one of FIG.1 but adapted to be moved over an existing pipeline to be insulated; and

FIG. 4 is a detail view of the dispenser of the apparatus of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of FIG. 1comprises a stationary frame 10 rotatably supporting a rotary ringdispenser 11 which can be rotated by an electric motor 12 through a belt13. The dispenser comprises a circularly extending trough-shaped portion14. A liquid, foamed polyurethane forming composition can be suppliedthrough a supply pipe 15 for discharge on a radially extending surfaceportion of the trough 14. Preferably the end portion of the supply pipe15 near the trough 14 is inclined so as to discharge the liquid onto thetrough 14 in the direction of the circumferential velocity of therotating trough. The frame 10 also carries a series of reel holders 16mounted around the dispenser in regular fashion and each holding a reel17 of continuous The frame further comprises a tubular guide 18 of whichan initial part is formed as a truncated cone 19 having its wide endlocated around the dispenser and having at its narrow end a cylindricalextension 20. The guide 18 is mounted coaxial with the dispenser 11. Atthe forward end of the cylinder 20 and coaxial therewith a calibrationdisc 21 of rubber or another flexible material is mounted. The singledisc 21 may be replaced by a plurality of flexible strips in circulararrangement. in order to reduce the friction between the insulation tobe formed and the guide 18, the cylindrical portion 20 is preferablymade as short as possible, the calibration mainly being effected by thedisc 21.

In operation a pipe 22 to be insulated is inserted through the dispenser11 and guide 18 in coaxial position therewith. The coaxial positioningof the pipe 22 in the assembly is facilitated if the central portion ofthe dispenser is designed as a bearing 23 for the pipe 22, aligning thepipe with the dispenser whilst allowing relative axial movement of thetwo. Alternatively, the pipe is aligned with centering wheels mounted tothe frame, as will be described later with reference to FIG. 3.

Paper sheets 24 are unwound from their reels 17 and drawn through guide18, whereby the sheets 24 on entering the conical portion 19 of theguide with their longitudinal edges overlap the edges of the adjacentsheet to form a fully enclosed surface around the trough 14 of thedispenser. On forward movement through the guide 18 the edges of thesheets will gradually overlap further until the narrow end of the cone19 is. reached from where the sheets form a tubular body or sleeve.

The flexible tubular body being sprayed with polyurethane is normallymade of paper sheets, but the tube can be formed of other flexiblematerials such as thin metal sheets or fabric webs. Normally the tubularbody is built together from several continuous sheets which are shapedto form an enclosure large enough to passover the dispenser.

The initial portion of the tubular body is preferably shaped as atruncated cone formed by moving the sheets with their longitudinal axiscoinciding with the generatrix of the cone 19, in a converging path. Atthe narrow end of the cone the sheets move further in parallelrelationship forming a cylindrical body. The dispenser is positionedwithin the wide end of the cone. During the time the sheets are movedforward forming a truncated cone the edges of the sheets are caused tooverlap increasingly. The composite tubular body can also be formed bywinding the sheet or sheets in a screw like fashion, but this method iscomplicated and therefore less desirable.

The sheets should be wide enough to ensure that the dispenser isentirely surrounded by the sheet material, leaving no holes between theedges of two adjacent sheets through which polyurethane could escape.

After rotation of the dispenser 11 by the motor 12 has started, thepolyurethane composition is supplied through the supply pipe 15 to thetrough 14. By the high rotational speed of the dispenser the liquidcomposition received thereon is driven to the circumference of thetrough 14 and is centrifugally discharged therefrom as a fine spray. Asthe liquid is flowing over the surface of the dispenser as a thin filmthe various components of the liquid are intensively mixed. Therefore,the components can be supplied individually to the dispenser, ifdesired. The homogeneous and uniform spray of liquid is received on theinner face of the sheets 24 opposite the dispenser, the sheets 24 beingexternally supported by the guide 18. While the liquid is sprayed, thepipe 22 is moved continuously in the axial direction as indicated by anarrow. The leading ends of the sheets 24 have been attached to thesurface of the pipe, so that simultaneously with the pipe 22 the sheets24 are drawn forward from the reels 17 through the guide 18. Thus, theportions of the sheets 24 on which the polyurethane liquid has beensprayed by the dispenser are moved towards the cylindrical part 20 ofthe guide. During this movement the polyurethane liquid on the sheetsexpands by foaming, so that in the cyl inder 20 the polyurethane foamfills the annular space between the cylinder 20 and pipe 22. On leavingthe cylinder 20 the foaming has been completed, so that around the pipea foamed polyurethane coating 25 has been formed which is accuratelyshaped by the cylinder 20 and of which the surface may be furthersmoothed by passage through the orificed disc 21. If necessary, the foamis allowed to harden on the pipe until it has become sufficiently rigidto handle the pipe.

Before any portion of the pipe 22 has been coated, the leading ends ofth sheets 24 must be connected to the pipe with an adhesive. Onceoperations are proceeding the sheets 24 become firmly bonded to thepolyurethane coating and remain thereon as a protective layer.

The rotary ring dispenser on being rotated around the pipe is capable ofdischarging the polyurethane liquid received on its surface as a finespray from its circumferential edge by centrifugal forces generated bythe rotation. In its simplest form the dispenser is a saucer shapedelement with a central opening through which the pipe has been inserted.The polyurethane liquid which is a mixture of various components isfurther homogenized as it flows over the surface of the dispenser. Theresidence time of the liquid on the ring is dependent on various factorssuch as size and design of the ring, its rotational speed, and theviscosity of the polyurethane liquid. Under otherwise constantconditions, the residence time of the liquid on the ring can beincreased by extending the surface of the ring with profiled portions,for example a curved rim. Generally the circumference of the dispenseris circular, but small serrations or other minor iregularities may beprovided if desired to control or improve the atomization of the liquidbeing discharged.

The apparatus of FIG. 2 is in many respects identical to the one of FIG.1, but there are a few differences in view of its intended use formaking loose pipe scales. For this reason, the centrally located pipe 26inserted through the dispenser 11 and guide 18 is no longer movedaxially but remains stationary. As used herein, the term pipe isintended to include a solid as well as a tubular member. The pipe 26serves as an internal sizing member or mandrel for the scales to beformed, and since the polyurethane foam will move along the stationarypipe 26 the surface thereof or the entire pipe is made of a material notadhering to the foam, for example polypropylene. The resulting productis a tubular insulation which is drawn forward by a pipe hauling device.At the same time the paper sheets bonded to the surface of theinsulation are drawn forward. The foamed insulation tube 27 can be cutlengthwise by circular blade saws 28 mounted on the frame and also insections of the desired length to form pairs of pipe scales ready formounting around a pipeline to be insulated.

The apparatus diagrammatically shown in perspective view in FIG. 3 is inprinciple similar to the apparatus of FIG. 1, but it has been designedas a vehicle adapted to travel over a pipeline.

Like the apparatus of FIG. 1 the apparatus of FIG. 3 comprises a frame30, rotary ring dispenser 31 having a trough-shaped section 34, a motor32 with belt 33 for rotatably driving the dispenser 31, reel holders 36,carrying reels 37 of flexible sheets 44, and a guide 38 comprising afrusto-conical part 39 and a cylindrical part 40. A section of thetrough 34 of the dispenser with supply pipe 35 for feeding thepolyurethane liquid thereon is shown in FIG. 4.

The apparatus does not receive the pipe to be coated in a bearing insidethe dispenser ring as in the design of FIG. I, but between centeringwheels 29 mounted in the frame. These wheels 29 align the pipe 42 withthe ring dispenser 31. One of the centering wheels is also a drive wheel41 which can be driven by an electric motor 43 to move the entireapparatus over the pipeline 42 (to the right in FIG. 3).

To ensure proper alignment of the apparatus with the pipeline, twogroups of the centering wheels 29 are provided', one group of threecentering wheels being connected to a vertical plate 46 of the frame anda second group of three centering wheels being connected to anothervertical plate of the frame some distance from the first plate,forexample plate 47 (wheels not shown). Power is supplied to theelectric motors 32, 43 and the polyurethane liquid is supplied to thesupply pipe 35 from a truck travelling along the pipe track. If it isdesired to mount the apparatus on a pipeline at a point between theterminals thereof. it is necessary to design the apparatus in twoseparable or hingeable halves. The operation of the apparatus of FIG. 3is the same as in FIG. 1, except that the pipe is now kept stationaryand the apparatus is being moved over it.

The invention is not limited to the production if insulations having acircular cross-section. Other shapes may be produced, for example squarecross-sections for making ducts.

What I claim is:

1. An apparatus for producing tubular foamed polyurethane insulation,said apparatus comprising:

a frame;

a rotary ring dispenser mounted on said frame for centrifugallydispensing a liquid foamable polyurethane composition, said dispenserhaving a central opening therein;

centering means carried by said frame for mounting a pipe coaxially withthe dispenser through the central opening thereof;

rotating means attached to said frame and operatively connected to saiddispenser for rotating said dispenser about its axis to centrifugallydispense a liquid foamable polyurethane composition;

supply means for feeding a liquid foamable polyurethane composition tosaid dispenser;

reel holding means rotatably mounted on said frame and adapted to carrya plurality of reels of sheet material in a regular spaced relationshipwith respect to the circumference of said dispenser; and

tubular support means mounted on said frame coaxially with saiddispenser for supporting the outer surface of said sheet material whendrawn off the reels and through the tubular support means, said tubularsupport means and said reels of sheet material being arranged relativeto said dispenser so that said liquid composition is dispensed onto theinner surface of said sheet material.

2. An apparatus as defined in claim 1 wherein the tubular support meanscomprises:

a conical section having its wide end disposed around said dispenser;and

a cylindrical section connected to the narrow end of the conical sectionand coaxial therewith.

3. An apparatus as defined in claim 2 wherein said frame is adapted totravel over the pipe inserted through the opening of the dispenser andfurther includes pipe engaging drive means for moving said framerelative to said pipe.

1. An apparatus for producing tubular foamed polyurethane insulation,said apparatus comprising: a frame; a rotary ring dispenser mounted onsaid frame for centrifugally dispensing a liquid foamable polyurethanecomposition, said dispenser having a central opening therein; centeringmeans carried by said frame for mounting a pipe coaxially with thedispenser through the central opening thereof; rotating means attachedto said frame and operatively connected to said dispenser for rotatingsaid dispenser about its axis to centrifugally dispense a liquidfoamable polyurethane composition; supply means for feeding a liquidfoamable polyurethane composition to said dispenser; reel holding meansrotatably mounted on said frame and adapted to carry a plurality ofreels of sheet material in a regular spaced relationship with respect tothe circumference of said dispenser; and tubular support means mountedon said frame coaxially with said dispenser for supporting the outersurface of said sheet material when drawn off the reels and through thetubular support means, said tubular support means and said reels ofsheet material being arranged relative to said dispenser so that saidliquid composition is dispensed onto the inner surface of said sheetmaterial.
 2. An apparatus as defined in claim 1 wherein the tubularsupport means comprises: a conical section having its wide end disposedaround said dispenser; and a cylindrical section connected to the narrowend of the conical section and coaxial therewith.
 3. An apparatus asdefined in claim 2 wherein said frame is adapted to travel over the pipeinserted through the opening of the dispenser and further includes pipeengaging drive means for moving said frame relative to said pipe.